(1) Field of the Invention
The invention relates to a television receiver of a type comprising a teletext decoding circuit and a storage means (page number memory) in which the page numbers associated with a plurality of teletext pages can be stored.
(2) Description of the Prior Art
Such a television receiver has several operating modes, more specifically a program-mode and a teletext mode. In the program mode the video signal transmitted by a transmitter is applied through a video channel to a picture screen for displaying the television program. In the teletext mode said video signal is applied through a teletext decoder circuit to the picture screen for displaying the teletext associated with the program. The television itself can be partly or wholly suppressed.
The operating mode is determined by the viewer, (user). To enable the viewer to inform the receiver about his wishes, the receiver includes a control system comprising external components which can be manipulated by the viewer. More specifically, this control system has a control panel with control keys, each having a specific control function. This function is indicated by a sign applied on, over or under the relevant control key. Thus, there are for example a volume control key, a luminance key, a teletext key, a mixed-mode key, a program key and a plurality fo figure keys etc. These last-mentioned keys are characterized in that the associated signs are numerals. If the receiver is in the program mode, the viewer can inform the receiver with the aid of the figure keys which program or channel is wanted. After the teletext or the mixed-mode key has been operated the set is in the teletext mode with a partly or wholly suppressed television program and the viewer keys-in the page number of the desired teletext page, using the same above mentioned keys.
Operation (or manupulating) of one or more of the keys on the control panel generally results in the generation of a control instruction by the control system. Such control instruction may include the page numbers of a desired teletext page. All these instructions are received by a control circuit which interprets these instructions and gives instructions to the different circuits to be controlled, including the teletext decoder circuit. More specifically, the teletext decoder receives a page number in response to which the required teletext page is captured, stored in a page memory and thereafther displayed on the picture screen by a character generator.
As is known a teletext index page is first displayed on the picture screen after a teletext key or the mixed-mode key has been operated. By selecting a desired page from this index and keying-in the associated page number with the aid of the numeric keys this teletext page is captured by the teletext decoder circuit and displayed thereafter.
If thereafter the display is required of a page associated with a different subject, the index page must usually again be consulted to find the page number of the relevant page. It should be borne in mind that each time the page number of a desired page is keyed-in it takes a certain period of time before the relevant page is displayed on the screen. It is therefore justified to state that such a television receiver is far from user-friendly. To improve this, it is proposed on page 527 of reference 1 to provide the receiver with a storage means which is coupled to the control circuit and in which a plurality of page numbers can be stored. This storage means will be referred to as the page number memory hereinafter.
By operating the control circuit, the user can store a first series of page numbers in a sequence in which he wants them to be displayed, in the page number memory. To enable the display in the desired sequence of these preselected teletext pages, the control panel has a key which will be called the read key hereinafter. Each time this key is operated, the control circuit receives an accurately defined operating instruction and a subsequent page number of the first series is read from the page number memory and applied to the teletext decoder circuit. In this way the teletext pages of the first series are sequentially displayed on the picture screen.
Thus, for this television receiver it is possible to select all those pages from an index page the viewer is interested in. The page corresponding numbers can be stored in the page number memory in the sequence in which the display of these pages is desired. Thereafter, they can be caused to appear in the desired sequence, one after the other, by pushing the read key once for every page.
It should be noted, that, after the read key has been operated, it also takes a certain time before the new page appears on the picture screen. However, by constructing the teletext decoder circuit in the way described in reference 1 or 2, a new page can be displayed immediately after pushing the read key. It is possible to couple to the teletext decoder circuit detailed in said reference a page memory having a capacity that no less than four pages can be stored therein simultaneously. All this is then organised such that this page memory contains the page actually displayed on the picture screen and also the three pages of the first series.
It should also be noted that the page number memory may be constituted by a non-volatile memory, so that the same series of teletext pages are permanently available. It is alternatively possible to use a volatile memory for this purpose, optionally in combination with a non-volatile page number memory.